Jens Berkmann

Bio: Jens Berkmann is an academic researcher from Infineon Technologies. The author has contributed to research in topics: MIMO & Orthogonal frequency-division multiplexing. The author has an hindex of 11, co-authored 46 publications receiving 323 citations. Previous affiliations of Jens Berkmann include Intel Mobile Communications.

On 3G LTE Terminal Implementation - Standard, Algorithms, Complexities and Challenges

Abstract: Currently, 3GPP standardizes an evolved UTRAN (E-UTRAN) within the Release 8 Long Term Evolution (LTE) project. Targets include higher spectral efficiency, lower latency, higher peak data rate when compared to previous 3GPP air interfaces. The air interface of E-UTRAN is based on OFDMA and MIMO in downlink and on SCFDMA in uplink Main challenges for a terminal implementation include efficient realization of the inner receiver, especially for channel estimation and equalisation, and the outer receiver including a turbo decoder which needs to handle data rates of up to 75 Mbps per spatial MIMO stream. We show that the inner receiver can nicely and straightforwardly be parallelized due to frequency domain processing. In addition to the computational complexity of even a simple linear equaliser, one of the challenges is an efficient implementation considering necessary flexibility for different MIMO modes, power consumption and silicon area. This paper will briefly overview the current LTE standard, highlight a functional data flow through the single entities of an LTE terminal and elaborate more on possible first implementation details, including sample algorithms and first complexity estimates.

Closed loop transmission with precoding selection in LTE/LTE-Advanced system

Abstract: Closed-loop transmission combined with MIMO (multiple-input multiple-output) and OFDM (orthogonal frequency division multiplexing) technologies have drawn most attentions during development of the 4G systems (fourth generation of mobile communication systems). In LTE (Long Term Evolution) and LTE-Advanced systems, which are proposed by 3GPP (Third Generation Partnership Project) to be the most competitive candidate for the 4G systems, the codebook based precoding scheme is deployed for realizing the closed-loop transmission concept. This scheme introduces the precoding matrix selection at the receiver and precoding operation at the transmitter and achieves a good tradeoff between the system complexity and the performance gain given by the closed-loop transmission. In this manuscript, the authors give a brief overview of the LTE/LTE-Advanced system downlink transmission. Furthermore, different precoding matrix selection criteria are discussed at the aim of optimal receiver design. Following the analytical and numerical results, the authors conclude that the minimum post mean squared error based criterion is the optimal candidate for precoding matrix selection at the receiver in LTE compliant systems.

On the physical layer performance with rank indicator selection in LTE/LTE-Advanced system

Abstract: The 3GPP (Third Generation Partnership Project) LTE (Long Term Evolution) and LTE-Advanced activities work toward the evolved UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access (E-UTRA), and the solution of IMT-Advanced (International Mobile Telecommunications) and systems beyond. The combination of OFDM (orthogonal frequency division multiplexing) and MIMO (multiple-input multiple-output) has been introduced into LTE and LTE-Advanced systems for achieving high system capacity. Furthermore, the closed-loop concept with codebook based precoding MIMO and transmission layers selection, termed as RI (rank indicator) selection have also been included to provide robust transmission in mobile wireless communication scenarios and increase the cell coverage. This manuscript focuses on the RI selection study and implementation in LTE and LTE-Advanced systems and illustrates the downlink performance evaluation and comparison with different RI selection schemes. According to the analytical and numerical results from an LTE and LTE-Advanced compliant simulator, the mutual information based scheme is chosen as the best candidate for RI selection.

On MIMO with successive interference cancellation applied to UTRA LTE

Abstract: The long term evolution of UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access, abbreviated as UTRA LTE, makes use of OFDM (orthogonal frequency division multiplexing) combined with MIMO (multiple-input multiple-output), termed MIMO-OFDM. The potential maximization of transmitted data rates has been considered a most beneficial feature of MIMO schemes. This maximization shall be strived for by spatial multiplexing. In particular, high data rates in the downlink have been considered desirable. Also, in view of an efficient implementation, the downlink requires a thorough assessment. Therefore, the authors will discuss the deployment of spatial multiplexing in the UTRA LTE downlink and will show that the performance of successive interference cancellation (SIC) based data detection techniques for MIMO-OFDM is beneficial.

MIMO Schemes in UTRA LTE, A Comparison

Abstract: The long term evolution of UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access, abbreviated as UTRA LTE, will be based on OFDM (orthogonal frequency division multiplexing). Furthermore, MIMO (multiple-input multiple-output) techniques have been considered as a means for the improvement of wireless connectivity. In wireless systems, high data rates in the downlink are desirable: Furthermore, with respect to an efficient implementation, the downlink requires a thorough assessment. In particular, the Alamouti and the V-BLAST (Vertical Bell Labs Layered Space Time) schemes are seen as interesting concepts. In this communication, the authors will compare these two MIMO schemes w.r.t. the achievable performance in the UTRA LTE downlink using up to two transmit and two receive antennas. Furthermore, the authors will discuss the deployment of spatial multiplexing in the UTRA LTE downlink and will show that the performance of successive interference cancellation (SIC) based data detection techniques for MIMO-OFDM is beneficial.

A Survey on the Successive Interference Cancellation Performance for Single-Antenna and Multiple-Antenna OFDM Systems

Abstract: Interference plays a crucial role for performance degradation in communication networks nowadays. An appealing approach to interference avoidance is the Interference Cancellation (IC) methodology. Particularly, the Successive IC (SIC) method represents the most effective IC-based reception technique in terms of Bit-Error-Rate (BER) performance and, thus, yielding to the overall system robustness. Moreover, SIC in conjunction with Orthogonal Frequency Division Multiplexing (OFDM), in the context of SIC-OFDM, is shown to approach the Shannon capacity when single-antenna infrastructures are applied while this capacity limit can be further extended with the aid of multiple antennas. Recently, SIC-based reception has studied for Orthogonal Frequency and Code Division Multiplexing or (spread-OFDM systems), namely OFCDM. Such systems provide extremely high error resilience and robustness, especially in multi-user environments. In this paper, we present a comprehensive survey on the performance of SIC for single- and multiple-antenna OFDM and spread OFDM (OFCDM) systems. Thereby, we focus on all the possible OFDM formats that have been developed so far. We study the performance of SIC by examining closely two major aspects, namely the BER performance and the computational complexity of the reception process, thus striving for the provision and optimization of SIC. Our main objective is to point out the state-of-the-art on research activity for SIC-OF(C)DM systems, applied on a variety of well-known network implementations, such as cellular, ad hoc and infrastructure-based platforms. Furthermore, we introduce a Performance-Complexity Tradeoff (PCT) in order to indicate the contribution of the approaches studied in this paper. Finally, we provide analytical performance comparison tables regarding to the surveyed techniques with respect to the PCT level.

Multi-core for mobile phones

Abstract: High-end mobile phones support multiple radio standards and a rich suite of applications, which involves advanced radio, audio, video, and graphics processing. The overall digital workload amounts to nearly 100GOPS, from 4b integer to 24b floating-point operations. With a power budget of only 1W this inevitably leads to heterogeneous multi-core architectures with aggressive power management. We review the state-of-the-art as well as trends.

On the way towards fourth-generation mobile: 3GPP LTE and LTE-advanced

Abstract: Long-TermEvolution (LTE) is the new standard recently specified by the 3GPP on the way towards fourth-generation mobile. This paper presents the main technical features of this standard as well as its performance in terms of peak bit rate and average cell throughput, among others. LTE entails a big technological improvement as compared with the previous 3G standard. However, this paper also demonstrates that LTE performance does not fulfil the technical requirements established by ITU-R to classify one radio access technology as a member of the IMT-Advanced family of standards. Thus, this paper describes the procedure followed by the 3GPP to address these challenging requirements. Through the design and optimization of new radio access techniques and a further evolution of the system, the 3GPP is laying down the foundations of the future LTE-Advanced standard, the 3GPP candidate for 4G. This paper offers a brief insight into these technological trends.

Data processing device and data processing method

Abstract: This technology pertains to a data-processing device and a data processing method that make it possible to ensure good communication quality when using an LDPC code to transmit data. In group-wise interleaving, an LDPC code having a code length (N) of 16,200 bits and a code rate (r) of 10/15 or 12/15 is interleaved on a per-bit-group basis, each bit group being 360 bits long. In group-wise deinterleaving, the interleaved LDPC code is restored to the original ordering thereof. This technology can be applied, for example, to data transmission or the like using an LDPC code.

On the Evolution of Multi-Cell Scheduling in 3GPP LTE / LTE-A

Abstract: This paper provides a holistic overview of multi-cell scheduling strategies in emerging wireless systems. Towards this objective, the evolution of interference management techniques is thoroughly investigated from simple inter-cell interference coordination (ICIC) techniques towards more advanced coordinated multipoint transmissions (CoMP), while comparing and contrasting their common features and differences. Finally CoMP is explored in detail as an advanced and challenging mechanism to fully cooperate between adjacent cells in order to have an efficient resource allocation and inter-cell interference mitigation in multi-cell environments.